1. Field of the Invention
The present invention relates to street sweepers or the like and more specifically relates to apparatus for maintaining a substantially constant pressure and pick-up broom pattern on a surface being swept for the useful life of the broom, which broom varies in size, weight and stiffness during its life due to wear.
2. Description of the Prior Art
Street sweepers and controls for operating the same are known and disclosed in the above referred to applications. The sweeper includes a main or pick-up broom which engages streets or the like to be swept. In the Kassai application a hydraulic cylinder is disclosed for raising and lowering the sides of the pick-up broom, and a pressure gauge located in the cab is connected to the cylinder thereby enabling the operator to maintain a light, medium, or heavy pick-up broom pressure on the surface being swept.
In the above type of sweeper, whether a three wheel or a four wheel sweeper, it is desirable to maintain a substantially constant pick-up broom sweeping pressure and pattern against the surface being swept during the life of the broom. It is well known that a new pick-up broom of about 36 inches in diameter is heavy and thus requires a lifting force acting thereon to provide the desired sweeping pressure and pattern. When the pick-up broom is worn to its minimum acceptable diameter of about 16 inches, the broom is much lighter and requires a downward force to provide the desired sweeping pattern. The pick-up broom is journaled on the ends of a pair of laterally spaced arms that are provided to the chassis of the sweeper and is pivotally moved between a raised transport position and a lowered working position against the surface to be cleaned by a hydraulic cylinder.